1. Field of the Invention
The present invention relates to a substrate processing apparatus and a method of processing a substrate.
2. Description of the Related Art
As disclosed in Japanese Patent Application Publication No. 2010-56470, a variety of films constituting semiconductor devices is demanded to be thinner and more uniform with miniaturization of circuit patterns in the semiconductor devices. What is called MLD (Molecular Layer Deposition) or ALD (Atomic Layer Deposition) is known as a film deposition method responding to the demand. In the method, a first reaction gas is absorbed on a surface of a substrate by supplying the first reaction gas to the substrate, and then the first gas adsorbed on the surface of the substrate is caused to react with a second reaction gas by supplying the second reaction gas to the substrate, thereby depositing a film composed of a reaction product of the first reaction gas and the second reaction gas on the substrate. According to such a method of depositing a firm, because the reaction gas can adsorb on the surface of the substrate in a (quisi-)self-saturation manner, high film thickness controllability, excellent uniformity, and excellent filling characteristics can be achieved.
However, with the miniaturization of circuit patterns, for example, filling a trench and a space is sometimes difficult even in the molecular layer deposition method with the increasing aspect ratio of the trench in a trench device separation structure or of a space in a line-and-space pattern.
For example, when trying to fill the space having a width of about 30 nm with a silicon oxide film, because the reaction gas is difficult to go to a bottom part of a narrow space, the film becomes thick in the vicinity of the upper end of a side wall of the line that partitions the space and becomes thin on the bottom part side. This sometimes causes a void to be generated in the silicon oxide film filling the space. For example, when such a silicon oxide film is etched in a subsequent etching process, an opening in communication with the void is sometimes formed in an upper surface of the silicon oxide film. On this occasion, contamination is liable to occur by allowing an etching gas (or an etching solution) to go into the void from the opening, or a defect is liable to occur by allowing metal to go into the void in a subsequent metallization process.
Such a problem can occur in CVD (Chemical vapor Deposition) without being limited to ALD. For example, when forming a conductive contact hole (so-called a plug) by filling a contact hole formed in a semiconductor substrate with a conductive material, a void may be generated in the plug. As disclosed in Japanese Patent Application Publication No. 2003-142484, to prevent this, a method is proposed of forming a conductive contact hole in which a void is reduced by repeating a step of removing overhangs projecting toward the center of the contact hole of the conductive material formed in the upper part or on the top of the contact hole when filling the contact hole with the conductive material by an etch back process.
However, in the invention disclosed in Japanese Patent Application Publication No. 2003-142484, because depositing the film of the conductive material and the etch back process have to be performed by different apparatuses, conveying a wafer between the apparatuses and stabilizing process conditions in each of the apparatuses take time, which causes a problem of not capable of improving the throughput.
Moreover, to solve the problem of the method disclosed in Japanese Patent Application Publication No. 2003-142484, Japanese Patent Application Publication No. 2012-209394 discloses a method of depositing a film and a film deposition apparatus capable of filling a concave-shaped pattern formed in a substrate surface with a film at high throughput while preventing a void from being generated in the film filled in the concave-shaped pattern. Japanese Patent Application Publication No. 2012-209394 discloses a film deposition apparatus that includes a turntable to receive a substrate, first and second reaction gas supply parts capable of supplying first and second reaction gases for film deposition to a substrate receiving surface of the turntable, respectively, and an activated gas supply part to activate and supply a modification gas for modifying a reaction product generated by reaction between the first and second reaction gases and an etching gas for etching, and a film deposition method of repeating a film deposition step and an etching step in sequence by rotating the turntable in the same process chamber by using the above film deposition apparatus.
However, in the film deposition method disclosed in Japanese Patent Application Publication No. 2012-209394, etching conditions such as an etching rate, surface roughness of an etched film and the like cannot be finely controlled, and setting optimum conditions with respect to a balance between the film deposition and the etching is difficult. Depositing a high-quality film has been sometimes difficult depending on a shape of the concave-shaped pattern (e.g., aspect ratio and the like) formed in the substrate surface, a type of film to be deposited and the like.